My stepmom got her comp infected with all kinds of viruses and now I have to clean it up. I booted into safe mode and installed Avast!, and did a boot scan. It pops up saying that explorer.exe has a virus, but it obvoiusly can't be deletd or moved, because then Windows can't run. This is the real explorer.exe, not a fake (its in the right directory). How do I fix it?